Active noise reduction (ANR) is the technology utilized in Pro Tech's award-winning NoiseBuster® Audio and NoiseBuster® Safety product lines.  The NoiseBuster Audio Headphones offer peace and quiet for consumers in environments containing low-frequency noise such as an aircraft cabin.  The NoiseBuster Safety Earmuff combines ANR with passive for maximum hearing protection in high-noise environments.

What is Active Noise Reduction (ANR)?
A NoiseBuster ANR system uses a microphone inside the ear cup (1) to listen to noise coming into the ear (2). Using electronics (3), the system takes that information and uses it to create a noise wave that is identical to, but directly opposite of, the one coming into the ear. The "anti-noise" wave is output through a speaker (4), also located in the ear cup. When the two waves (the noise wave and the anti-noise wave) meet, the noise is significantly reduced (5).
 

NoiseBuster Safety Earmuff ANR Protection
NoiseBuster ANR is the most effective defense against low frequency noise. Low frequency noise consists of powerful sound waves that can travel great distances and cannot be absorbed by conventional passive materials. Noises generated by engines, fans, motors and other similar devices are typically dominated by low frequencies--frequencies that cannot be stopped by passive earmuffs.

In addition to the detrimental effect it has on hearing, low-frequency noise creates another,  perhaps even more serious effect. Because low-frequency noise masks speech, it is difficult for a person to hear and comprehend speech and warning signals when exposed to such noise.